In the prior art, various means of securing wire mesh screens for window and doors to frames of aluminum, stainless steel, or similar material, including means by which resistance is maximized against attempts to pull or rip the screen from the frame and by which tension of the screen is maintained, are known. To construct screens with a light screen mesh, the mesh is attached to the screen frame by use of a roller which forces a cylindrically shaped rubber strip over the mesh lengthwise near the edge of the mesh and into a groove in the frame, so that the mesh is wedged tightly in the groove between the frame and the rubber strip.
For heavier weight mesh materials, these means of securing a screen to its frame include the use of a tension retainer bar, whereby the edges of the screen are sandwiched between the longer arm of an L-shaped frame and the tension retainer bar, and regularly-spaced fasteners (e.g. metal screws) are driven through the retainer bar, the screen, and the retainer wall of the frame along the entire length of the edges of the screen. In addition, there may be slightly raised ridges on, and running the full length of, the underside of the retainer bar and the surface of the frame, abutting tightly against the screen mesh. In this manner, the screen is secured by pressure applied to a more or less even extent along the entire length of its edges and over a width more or less equal to the width of the retainer bar, rather than concentrating the holding pressure of the screen to the points at which the fasteners are inserted through the screen which would expose the screen locally to sheer tears.
It is also known in the prior art to equip a screen frame (whether rectangular or L-shaped) with vinyl or felt extender tongues which extend out from the frame on the same plane as the screen mesh, in order to compensate for any gap occurring between the frame of an installed screen and the frame of the structure into which the screen is installed. The vinyl or felt tongue is held in place by means of a "T" groove running the length of the outside edge of the frame and into which is inserted the "T"-shaped base of the vinyl or felt extender tongue.
In lieu of an extender tongue inserted directly on the main screen frame, there is known in the prior art the use of an extender frame constructed of aluminum, stainless steel, or similar metal or metal alloy and which is attached to a cross-sectionally rectangular (but not L-shaped) main screen frame. Such an extender frame is generally cut to the same length as the vertical side of the main screen frame to which it is to be attached, and cross-sectionally is constructed in the shape of a "U", with square rather than curved corners (inside and outside), in order to fit lengthwise over the edge of the rectangular main screen frame. Each length of extender frame is provided with two rather than one vinyl or felt extender tongues, installed as described above, with one extender tongue extending outward in the same plane as the screen mesh as described above (the "first" tongue), and the other extender tongue extending perpendicularly to one side of the plane of the screen mesh (the "second" tongue), but running lengthwise in the same direction as the first extender tongue.
The extender frame was used to compensate for sizing of a standard form screen, such compensation occurring in the plane of the screen mesh between the main screen frame and the structure into which the screen is installed. In addition, however, the extender frame allowed the screen to seal in a second direction or plane.
There is further known in the prior art various designs of metal screen window and door frames in which a horizontal brace anchoring the bottom of an upper screen section and the top of a lower screen section (or a vertical brace anchoring left and right screen sections) is used. The ends of the horizontal brace are attached to the vertical jambs of the screen frame by any of a number of means, and the capacity of the brace to hold the upper and lower screen sections varies according to the method of attachment used.
It is the object of this invention to teach improvements to the design of screens used for windows, doors, porches, etc., including but not limited to increasing the screen frame's grip of the screen mesh when a tension retainer bar as described above is used, and facilitating the construction of a screen that uses a tension retainer bar.
It is a further object of the present invention to introduce new and unique applications and combinations of vinyl or felt extender tongues extending directly from the screen frame.
It is yet another object of the present invention to strengthen the bracing capacity of horizontal or vertical center braces of screen windows and doors and other screen frames.